KR102538729B1 - Vacuum Deposition Equipment and Methods for Coating Substrates - Google Patents

Abstract

The present invention relates to a vacuum deposition installation (1) for continuously depositing coatings formed from a metal or metal alloy on a moving substrate (S), said vacuum deposition installation comprising: supplying metal or metal alloy vapor; a vaporization crucible (4) suitable for carrying out and comprising a vaporization pipe (7); - a deposition chamber (2) suitable for causing the substrate (S) to travel along a given path (P); a vapor jet coater (3) linking a vaporization pipe to the deposition chamber, said vapor jet coater comprising: - a re-division chamber (31), which transversely said repartitioning chamber (31), comprising at least one reheating means (33) extending from and across the width of said given path and positioned within said repartitioning chamber, and - a steam outlet orifice (32), said steam outlet An orifice (32) has a base opening (9) linking the vapor outlet orifice to the subdivision chamber, a top opening (10) through which vapor can exit the deposition chamber and linking the base opening to the top opening. and two sides (11, 12) of which the sides of the steam outlet orifice converge towards each other in the direction of the top opening, further comprising the steam outlet orifice (32).

Description

Vacuum Deposition Equipment and Methods for Coating Substrates

The present invention relates to a vacuum deposition plant for depositing on a substrate coatings formed from a metal or metal alloys, for example zinc and zinc-magnesium alloys, the plant more particularly coating a steel strip. It is intended to, but is not limited thereto. The invention also relates to a method for coating the substrate.

BACKGROUND OF THE INVENTION Various processes are known for depositing metallic coatings composed of alloys in the end, on a substrate, such as a steel strip. Among these, mention may be made of hot-dip coating, electrodeposition and also various vacuum deposition processes, for example vacuum deposition and magnetron sputtering.

Methods are known from WO97/47782 and WO2009/047333 for continuous coating of steel substrates in which a metallic vapor spray propelled at speeds greater than 500 m/s is brought into contact with the substrate. Nevertheless, it has been found that zinc vapors tend to condense and this causes defects such as microdroplets in and on metallic coatings.

It is therefore an object of the present invention to address the disadvantages of prior art processes and installations by providing a vacuum deposition facility which prevents condensation of metal or metal alloy vapors.

To this end, the first subject of the present invention relates to a vacuum deposition facility for continuously depositing coatings formed from metal or metal alloy on a moving substrate, wherein the vacuum deposition facility supplies metal or metal alloy vapor. a vaporization crucible adapted to form a vaporization pipe and comprising a vaporization pipe, a deposition chamber suitable for driving the substrate through a given path and a vapor jet coater linking the vaporization pipe to the deposition chamber; , the steam jet coater,

- a repartitioning chamber, the repartitioning chamber extending transversely from the vaporization pipe and across the width of the given path and comprising at least one reheating means positioned within the repartitioning chamber; and

- a vapor outlet orifice, comprising a base opening linking the vapor outlet orifice to the redivision chamber, a top opening through which vapor can exit the deposition chamber and linking the base opening to the top opening. and two sides of the steam outlet orifice converging towards each other in the direction of the top opening.

The installation according to the invention may also have the optional features listed below individually or in combination.

- the steam outlet orifice is trapezoidal in cross section along a plane perpendicular to the length of the steam outlet orifice;

- the steam outlet orifice is isosceles trapezoidal in cross section along a plane perpendicular to the length of the steam outlet orifice;

- the base angle of the isosceles trapezoid has a value greater than 60°,

- the sides of the steam outlet orifice exponentially converge toward each other in the direction of the top opening;

- the angle between the base opening and the respective side has a value greater than 60° at the exit of the steam outlet orifice;

- the ratio between the width of the base opening and the width of the top opening of the steam outlet orifice is between 1.6 and 2.4;

- the ratio between the side length and the base opening width is between 4 and 8;

Other features and advantages of the present invention will be described in more detail in the description that follows.

The present invention will be better understood upon reading the following description, which is provided by reference and for purposes of explanation only and is not intended to be limiting.

- Figure 1 shows a cross-section of an embodiment of a plant according to the invention.
- Figure 2 shows a cross section of an embodiment of a steam jet coater according to the invention.
- Figure 3 is the result of numerical modeling comparing the prior art and the present invention.

As used in this application, the terms "lower", "below", "inward", "inwardly", "outwardly", "outwardly", "upstream", and "downstream" mean that the facility is It should be noted that reference is made to the positions and orientations of the different components of the plant when installed in a vacuum deposition line.

It is an object of the present invention to deposit coatings formed from metals or metal alloys onto a substrate. The aim is in particular to obtain zinc or zinc-magnesium coatings. However, the process preferably includes, but is not limited to, any coating based on one single metal or metal alloy whose elements have vapor pressures at the bath temperature that do not differ by more than 10%, because This is because control of their respective relative contents is then facilitated.

Mention may therefore be made of coatings made of zinc as the main element, and of, for example, chromium, nickel, titanium, manganese, magnesium, silicon and aluminum, considered individually or in combination, as additional element(s). there is.

The thickness of the coating is preferably between 0.1 and 20 μm. On the other hand, if the thickness is less than 0.1 μm, there is a risk that corrosion protection of the substrate will be insufficient. On the other hand, it is not necessary to go above 20 μm to have the level of corrosion resistance required, especially in the automotive or construction sector. Generally, the thickness may be limited to 10 μm for automotive applications.

Referring to Figure 1, an installation 1 according to the present invention initially comprises a deposition chamber 2 and means for driving a substrate through the chamber.

This deposition chamber 2 is preferably a hermetically-sealable box maintained at a pressure of 10 ⁻⁸ to 10 ⁻³ bar. It has an entry lock and an exit lock (these not shown) which can travel along a given path P in the direction in which the substrate S, eg a steel strip, travels.

The substrate S can be driven by any suitable means depending on the shape and nature of the substrate. A rotary support roller 3 on which a steel strip can be supported can in particular be used.

In the deposition chamber 2, next to the side of the substrate S to be coated, there is a vapor jet coater 3. This coater is suitable for spraying the metal alloy vapor coming out of the vaporization crucible 4 onto the traveling substrate S.

The vapor jet coater (3) is mounted directly on the vaporization crucible (4) or not. The vaporizing crucible is suitable for receiving a metal or metal alloy bath generating vapor to be deposited on the substrate S and for supplying the metallic vapor to a vapor jet coater. The vaporization crucible (4) is preferably located in the deposition chamber (2).

The vaporization crucible 4 mainly consists of a port 5, a cover 6 and a vaporization pipe 7 connected to the cover on one side and to the steam jet coater 3 on the other side. Preferably, a valve located between the vaporizer and the ejector controls the metallic vapor flow. These different parts can be made of graphite, for example.

The vaporization crucible 4 is provided with heating means 8 which makes it possible to form metallic vapor and provide it to the vapor jet coater 3 . The vaporization crucible 4 is advantageously provided with an induction heater which has the advantage of facilitating stirring and compositional homogenization of the metal alloy bath.

The steam jet coater 3 is preferably a sonic steam jet coater, that is, a coater capable of generating a sonic speed steam jet. This type of coater is also commonly referred to as a JVD (Jet Vapor Deposition) device. The reader may refer to patent applications WO97/47782 and WO2009/047333 for a more complete description of the details of this type of device.

The vapor jet coater 3 advantageously comprises a repartitioning chamber 31 provided with a narrow vapor outlet orifice 32, the length of which is close to the width of the substrate to be coated. The repartitioning chamber allows for a homogeneous distribution of the metallic vapor along the width of the substrate. Practically speaking, it extends transversely from the vaporization pipe 7 when the plant is running and across the width of the path P, ie across the substrate width. It preferably extends parallel to path P such that all points of the substrate are equidistant from the steam jet coater which further favors homogeneity of the coating deposition. It is preferably in the form of a tube extending longitudinally across path P. Such a chamber may be made of graphite, for example.

The repartitioning chamber further comprises at least one reheating means 33 positioned within the repartitioning chamber, ie in a cavity bounded by the sides of the repartitioning chamber 31 . It allows reheating the vapor coming out of the vaporization pipe after the vapor has been expanded as it enters the re-division chamber. It thus prevents condensation in the repartitioning chamber. The reheating means extends along the length of the repartitioning chamber, preferably along the entire length. It is preferably in the form of a heating cartridge. The position and number of reheating means can be adjusted to optimize reheating of the steam.

The steam outlet orifice 32 is essentially a slot which can be adjusted in length and width, preferably. The possibility to adjust its width allows the vapor jet to be maintained within a wide range of vaporized metal surface temperatures and thus a wide range of vaporization rates. Additionally, the possibility of adjusting its length relative to the width of the substrate to be coated makes it possible to minimize the loss of vaporized metal.

Referring to Figure 2, in a cross section along a plane perpendicular to its length, the steam outlet orifice has a base opening 9 cut in the wall of the repartitioning chamber 31 to link the steam outlet orifice to the redivision chamber, the steam It includes a top opening 10 through which the position chamber can be entered and two sides 11, 12 linking the base opening to the top opening. The top opening 10 is preferably located in a plane parallel to the path P so that the metal or metal alloy vapors are deposited more homogeneously on the substrate.

Surprisingly, the risk of condensation of metal or metal alloy vapors in the vapor jet coater 3 and in the vaporizing pipe 7 is reduced if the sides 11, 12 of the vapor outlet orifice 32 converge towards each other in the direction of the top opening. It was found by the present inventors that it is effectively prevented. Without being bound by any scientific theory, the inventors believe that this width restriction at the exit of the steam outlet orifice 32 has the effect of localizing sonic shock at the exit of the steam outlet orifice 32 preventing condensation before that point. understand that you have

"Converging towards each other" means that the top opening width of the steam outlet orifice is smaller than the base opening width. It does not limit the shape of the sides. The sides can be, for example, straight lines, curved lines or a combination of both.

According to the first variant of the present invention, the shape of the steam outlet orifice 32 in cross section is trapezoidal. In that case, considering the general shape of the orifice, this means that a trapezoidal small base is located at the exit of the steam outlet orifice 32 . This linear shortening of the orifice assists in accelerating the steam jet uniformly and progressively. From an industrial point of view, this shape provides a good compromise between ease of manufacture and efficiency.

More preferably, the shape of the steam outlet orifice 32 in cross section is an isosceles trapezoid, ie a trapezoid in which the sides 11 and 12 have the same length and the base angles have the same dimensions. Due to the reflection symmetry, the steam jet exiting the steam outlet orifice is more homogeneous.

Preferably the base angle has a value greater than 60°, more preferably greater than 80°. This assists in focusing the vapor jet at the substrate.

Preferably, the ratio between the base opening 9 and the top opening 10 of the steam outlet orifice is between 1.6 and 2.4. It has been found that this makes the sonic impact effective at the exit of the steam outlet orifice while minimizing the pressure loss resulting from the shape of the orifice.

Preferably, the ratio between the side length and the base opening width is between 4 and 8. Due to this ratio, the positive lines of the vapor jets have time to stabilize after being disturbed at the junction between the re-division chamber 31 and the vapor outlet orifice 32.

According to the second variant of the invention the sides 11 , 12 of the steam outlet orifice 32 exponentially converge towards each other in the direction of the top opening 10 . “Exponentially converging” means that each side has an exponential shape in cross section. This shape favors the transition between the repartitioning chamber and the vapor outlet orifice. The flux lines of the steam jet are therefore less obstructed than at the junction between the repartition chamber and the steam outlet orifice.

Preferably, the two sides 11, 12 have the same exponential shape. Due to the reflection symmetry, the steam jet exiting the steam outlet orifice is more homogeneous.

Preferably, the angle between the base opening 10 and the side has a value greater than 60°, more preferably greater than 80° at the exit of the steam outlet orifice. This assists in focusing the vapor jet at the substrate.

preferably. The ratio between the width of the base opening 9 and the width of the top opening 10 of the steam outlet orifice is 1.6 to 2.4. It has been found that this makes the sonic impact effective at the exit of the steam outlet orifice while minimizing the pressure loss resulting from the shape of the orifice.

Preferably, the ratio between the side length and the base opening width is between 4 and 8. Due to this ratio, the flux lines of the steam jet have time to stabilize after being disturbed at the junction between the re-division chamber and the steam outlet orifice.

In both variants, the width of the top opening 10 is adjusted according to the required flow rate in the industrial vacuum deposition installation. A person skilled in the art will know how to adjust this width according to other parameters controlling the flow rate, especially based on numerical modeling.

In both variants, the width of the base opening 9 and the width of the top opening 10 are preferably along the length of the vapor outlet orifice 32 to favor homogeneous deposition of metal or metal alloy vapors in the substrate. constant

Preferably, the two sides 11, 12 of the vapor outlet orifice are heated to limit the risk of condensation of metal or metal alloy vapors on them.

Numerical modeling was performed to evaluate the effectiveness of a facility incorporating a steam outlet orifice according to the present invention.

The model applies to a facility comprising a vaporization pipe 7 connected to a vapor jet coater 3 comprising an extraction chamber 31 provided with a narrow vapor outlet orifice 32. Specifically, the model was applied based on the following values:

- metals to be vaporized: zinc,

- pressure at the entry of the vaporization pipe: 5869 Pa;

- Temperature at the entrance of the vaporization pipe: 953K

- Sides temperature: 1042K

- Zinc flow: 170 g/s

- fully open steam valve

Figure 3a) shows the results obtained with a steam outlet orifice 32 of rectangular cross section, the base opening and the top opening being both 24 mm, and the orifice having a length of 1750 mm.

Figure 3b) shows the results obtained with the steam outlet orifice 32 whose cross section is isosceles trapezoidal, the base opening is 48 mm, the top opening is 24 mm and the sides are 100 mm.

For both figures, the gray level represents the risk of condensation. If it is darker, it indicates a higher risk of condensation.

As is evident when comparing FIGS. 3 a) and 3 b), zinc condenses on the rectangular outlet orifice while not condensing on the trapezoidal outlet orifice.

The plant according to the invention applies more specifically to, but is not limited to, the treatment of pre-coated or bare metal strips. Of course, the process according to the present invention can be used for any coated or uncoated substrate, for example aluminum strip, zinc strip, copper strip, glass strip or ceramic strip.

Claims (8)

As a vacuum deposition facility (1) for continuously depositing coatings formed from metal or metal alloys on a moving substrate (S),
The vacuum deposition equipment,
- a vaporization crucible (4) suitable for supplying metal or metal alloy vapor and comprising a vaporization pipe (7);
- a deposition chamber (2) suitable for driving the substrate (S) therethrough along a given path (P) and
- a vapor jet coater (3) linking the vaporization pipe to the deposition chamber;
The steam jet coater,
- a repartitioning chamber 31, which extends transversely from the vaporization pipe and across the width of the given path and at least one reheating means in the form of a heating cartridge positioned in the repartitioning chamber ( 33), the re-partitioning chamber 31, and
- a vapor outlet orifice (32), a base opening (9) linking the vapor outlet orifice to the repartitioning chamber, a top opening (10) through which vapor can exit the deposition chamber ) and two sides (11, 12) linking the base opening to the top opening, the sides of the steam outlet orifice converging towards each other in the direction of the top opening. ), vacuum deposition equipment further comprising. According to claim 1,
The vapor outlet orifice is trapezoidal in cross section along a plane perpendicular to the width direction of the given path. According to claim 2,
Wherein the steam outlet orifice has an isosceles trapezoidal cross section along a plane perpendicular to the width direction of the given path. According to claim 3,
The base angle of the isosceles trapezoid has a value exceeding 60 °, vacuum deposition equipment. According to claim 1,
wherein the sides (11, 12) of the vapor outlet orifice (32) converge exponentially toward each other in the direction of the top opening (10). According to claim 5,
wherein the angle between the base opening (9) and each side (11, 12) has a value exceeding 60° at the exit of the steam outlet orifice. According to any one of claims 1 to 6,
wherein the ratio between the width of the base opening (9) and the width of the top opening (10) of the vapor outlet orifice is 1.6 to 2.4. According to any one of claims 1 to 6,
The ratio between the side length and the base opening width is 4 to 8, vacuum deposition equipment.

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